This document provides an overview of communications and networks. It discusses the components required for successful communications including sending and receiving devices. It describes different types of networks including LANs (local area networks), MANs (metropolitan area networks), and WANs (wide area networks). It also differentiates between client/server and peer-to-peer network architectures. The document aims to help readers understand computer communications and networking concepts.

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Communications and
Networks
Internet Resources

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Unit Objectives
 After completing this chapter you will be able to:
 Discuss the purpose of the components required for successful
communications and identify various sending and receiving devices
 Describe various uses of computer communications
 List the advantages of using a network, and differentiate among
LANs, MANs and WANs
 Differentiate between client/server and peer-to-peer networks, and
describe how P2P networks work

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Unit Objectives
 Differentiate among a star, bus, and ring network
 Describe the various network communications standards
 Explain the purpose of communications software
 Describe commonly used communications devices
 Discuss different ways to set-up a home network
 Describe various physical and wireless transmission media

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Communications
Communications and Networks

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Communications
 Computer communications describes a process in which two or
more computers or devices transfer data, instructions, and
information
 Today, even the smallest devices can communicate with each
other – often via the Internet

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Communications
 For successful communications you need:
 A sending device that initiates an instruction to transmit data,
instructions or information
 A communication channel or transmission media on which the data,
instructions, or information travel
 A communication device that connects the communications channel
to a receiving device that accepts the transmission

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Uses of Communications
Communications and Networks

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Uses of Communications
 Computer communications are everywhere
 Many require that you subscribe to an Internet access provider
 With others, organizations such as a business or school provide the
communications services

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Summary of Communications
Previously Discussed
Communications Previously Discussed
Blogs Newsgroups
Chat Rooms RSS
E-Mail Video Conferencing
Fax VoIP
FTP Web 2.0
Instant Messaging Wikis

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Wireless Messaging Services
 Users can send and receive wireless messages to and from
smartphones, cell phones, and handheld game consoles using
three techniques
 Text messaging
 Picture/Video messaging, and
 Wireless Instant Messaging
 The type of messaging depends on the on the services offered
by your wireless Internet service provider, or WISP

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Text Messaging
 A mobile device with text messaging allows users to send and
receive short text messages on a phone or other mobile device
 Services allow the user options to send and receive:
 Mobile to Mobile
 Mobile to E-Mail
 Web to Mobile, and
 Mobile to Provider

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Picture/video messaging
 With picture messages users can pictures and sound files, as
well as short text messages, to another device
 With video messages users can send short, about :30, videos
is addition to other type of messages
 Smart phones and other devices using MMS, typically have a
built-in camera
 As a consumer, you should be aware of memory availability and
camera quality

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Wireless Instant Messaging
 Wireless instant messaging (IM) is a real-time communications
service that allows mobile devices to exchange messages with
other online users
 Some WISPs partner with IM services
 AT&T allows communications through AIM, Windows Live
Messenger, and Yahoo! Messenger

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Wireless Access Points
 People connect everyday to wireless access points using their
mobile devices to access Internet-based services
 Two Types:
 Hot Spots, &
 Mobile Wireless Networks

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Hot Spots
 Is a network that provides wireless Internet connections to
mobile devices
 Three technologies
 Wi-Fi (local, within a building or room)
 WiMax (regional, withing a community)
 Bluetooth (location-based hot spots)
 Some hot spots are free, schools & coffee shops, and some are
subscription-based

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Mobile Wireless Network
 Provided by cell phone companies, for their devices to access
their networks
 Coverage and speed depends on the carrier
 Most common speed is 3G
 “4G” networks are becoming available

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GPS
 Short for Global Positioning System
 Uses satellite triangulation to pinpoint a location usually within
10-100 meters
 Examples
 Smart phones
 Car Navigation systems
 Handheld systems for hiking
 Access to additional features

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Geocaching
 Geocaching is a real-world outdoor treasure hunting game.
 Players try to locate hidden containers, called geocaches,
using GPS-enabled devices and then share their experiences
online.
 www.geocaching.com

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Collaboration
 People use the Internet to collaborate, or work together online
 Methods of collaboration
 E-mail
 Collaborative Software
 Document Management Systems

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E-mail
 Oldest form of collaboration
 Users send information and documents back and forth through
their e-mail accounts
 Pros
 Quick and inexpensive
 Cons
 Creates multiple versions of a document
 Information can get lost in the mix

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Collaborative Software
 Tools that enable users to share documents via online
meetings and communicate with other connected users
 Sometimes called a Web Conference or Web Meeting
 Examples
 Microsoft Groove or Office Live Meeting
 WebEx
 Google Apps
 GoToMeeting

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Document Management Systems
 Provides storage and management of a users documents
 Users can be granted access to each others documents
 Only one document exists, not multiple versions
 Examples
 Windows Live SkyDrive
 Google Docs

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Cybercafés
 Also know as an Internet Café, is a location, usually a
coffeehouse or restaurant, that provides Internet access to its
customers
 Examples
 Starbucks
 Burger King
 McDonalds

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Web Services
 A Web service is a method of communication between two
electronic devices over the web.
 The service can be integrated into any web page so users can
easily access it
 They do not require a specific programming language, operating
system or web browser
 Examples
 Google Apps, Google Cloud Print, Office 365

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Networks
LANs, MANs, and WANs
Network Architectures
Network Topologies
Intranets

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Networks
 A network is a collection of computers and devices connected
together via communications devices and transmission media
 A network can be internal to an organization or span the entire
world
 Why network?
 Facilitating communications
 Sharing hardware
 Sharing data and information
 Sharing software
 Transferring funds

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LANs, MANs, & WANs
 Networks can be classified is three categories
1. Local Area Network
2. Metropolitan Area Network
3. Wide Area Network

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Local Area Network (LAN)
A network that connects computers and devices in a limited geographical
area, such as a home, computer lab, or office building

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WLAN
 A wireless LAN is a LAN that uses no physical wires
 Computers and devices that access a WLAN must have built-in
wireless capability, or an appropriate adapter
 Very often WLANs are setup side-by-side with a traditional LAN

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Metropolitan Area Network (MAN)
 A high-speed network that connects local area networks in a
metropolitan area such as a city or town
 A MAN typically includes one or more LANs but covers a
smaller geographic area then a WAN
 Managed by a Network Provider such as a state government,
telephone company, or cable provider

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Wide Area Network (WAN)
 Network that covers a large
geographic area, such as a city,
country or the world
 A WAN can be one large
network or consist of two or
more LANs
 The Internet is the worlds
largest WAN

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Network Architectures
The design of computers, devices, and media in a network,
sometimes called network architecture, is categorized as either
client/server or peer-to-peer

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Client/Server
 On a client/server network, one or more computers act as a
server, and the other computers request services from the
server
 A server, sometimes called a host computer, control access to
the hardware, software, and other resources on the network
 The clients are other computers or mobile devices on the
network that rely on the server for its resources

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Peer-to-Peer
 Simple, inexpensive network
that typically connects fewer
than 10 computers or other
devices
 Each computer, or peer, has
equal responsibilities and
capabilities
 Each computer stores files on
its own hard drives for sharing
 Ideal for very small businesses
and home networks

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Internet Peer-to-Peer
 P2P describes an Internet network on which users access each
other’s hard disks and exchange files
 Sometimes called a file-sharing network
 Examples:
 BitTorrent
 Gnutella
 Kazaa
 LimeWire
 Responsible for the majority of illegal file-sharing on the
Interent

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Network Topologies
Star
Bus
Ring
Intranets

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Network Topologies
 A network topology refers to the layout of computers and
devices in a communications network
 Three most common topologies:
1. Star
2. Ring, and
3. Bus
 Most networks, including the Internet, use a combination of the
three

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Star Network
 All of the computers and Node Hub/Switch
devices, called nodes, connect
to a central device, usually
called a hub or a switch
 All data is transferred through
the hub or switch
 Fairly easy to install
 Nodes can be added and
removed without affecting the
rest of the network

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Bus Network
Bus
 Consists of a central cable to
which all computers and other
devices connect
 The bus is the physical cable
that connects everything
 Popular because they are
inexpensive and easy to install
 Devices can be added,
removed, and moved with ease
 If the bus fails, the entire
Node network goes down

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Ring Network
Node
 A cable forms a closed loop, or
ring, with every device
 Data travels from device to
device on the ring until it
reaches its destination
 If one device fails, the entire
network could possibly go down

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Intranets
 An intranet is an internal network that uses Internet
technologies
 Intranets usually make company information accessible to
employees
 Examples:
 Telephone directories
 Event calendars
 Job postings
 Video conferencing
 Accessed through a web browser where changes can be made
by everyone

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Network Communication
Standards
Ethernet UWB
Token Ring IrDA
TCP/IP RFID
Wi-Fi WiMAX
Bluetooth WAP

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Network Communication Standards
 Today’s networks connect a variety of devices across many
different networks, such as wide area, local area and wireless.
 All networks must use similar techniques for connecting
devices to ensure compatibility
 Two regulating organizations
1. ANSI
2. IEEE
 These organizations propose, develop, and approve network
standards

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Network Communications
Standards
 A network standard defines guidelines that specify:
 The way computers access the medium to which they are attached,
 The type(s) of medium used,
 The speeds used on different types of networks, and
 The type(s) of physical cable and/or the wireless technology used
 A that standard outlines characteristics of how two networks
communicate is called a protocol

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Widely Used Standards & Protocols
 You are to choose a standard or protocol below to research on
a and report to the class
1. Ethernet
2. Token Ring
3. TCP/IP
4. Wi-Fi
5. Bluetooth
6. UWB
7. IrDA
8. RFID
9. WiMAX
10. WAP